关键词：系统恢复；系统状态转移；备份恢复
摘 要：Achieving business continuity (that is, making sure that your critical business functions canbe performed in the face of a disaster) is always a tricky business. Designing systems to beavailable in the face of failure is one of the most complex problems in software engineering. Evenunderstanding what business continuity and disaster recovery mean is where things just beginto get complicated.For example, what most users mean when they discuss disaster recovery is the ability to get a siteup and running in a matter of minutes (or, at most, hours) from a last good state of an existingsystem in the case of a catastrophic failure where an entire data center is lost.Because such definitions can be so loose, it’s useful to define some terms for discussing businesscontinuity for IBM PureApplication System. Wikipedia, in its article on disaster recovery, refers totwo key measurements that are important to understand:Recovery point objective (RPO) is the measure of the maximum time period in which datamight be lost from an IT service due to a major incident.